Fix super ==: Test first for null before call inf super ==.

runtime/vm/flow_graph_compiler_x64.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/flow_graph_compiler.h"
 
 #include "lib/error.h"
@@ skipping 1124 matching lines @@
 void FlowGraphCompiler::EmitEqualityRegConstCompare(Register reg,
                                                     const Object& obj) {
   if (obj.IsSmi() && (Smi::Cast(obj).Value() == 0)) {
     __ testq(reg, reg);
   } else {
     __ CompareObject(reg, obj);
   }
 }
 
 
+// Implement equality spec: if any of the arguments is null do identity check.
+// Fallthrough calls super equality.
+void FlowGraphCompiler::EmitSuperEqualityCallPrologue(Register result,
+                                                      Label* skip_call) {
+  const Immediate raw_null =
+      Immediate(reinterpret_cast<intptr_t>(Object::null()));
+  Label check_identity, fall_through;
+  __ cmpq(Address(RSP, 0 * kWordSize), raw_null);
+  __ j(EQUAL, &check_identity, Assembler::kNearJump);
+  __ cmpq(Address(RSP, 1 * kWordSize), raw_null);
+  __ j(NOT_EQUAL, &fall_through, Assembler::kNearJump);
+
+  __ Bind(&check_identity);
+  __ popq(result);
+  __ cmpq(result, Address(RSP, 1 * kWordSize));
+  Label is_false;
+  __ j(NOT_EQUAL, &is_false, Assembler::kNearJump);
+  __ LoadObject(result, bool_true());
+  __ Drop(1);
+  __ jmp(skip_call);
+  __ Bind(&is_false);
+  __ LoadObject(result, bool_false());
+  __ Drop(1);
+  __ jmp(skip_call);
+  __ Bind(&fall_through);
+}
+
+
 void FlowGraphCompiler::LoadDoubleOrSmiToXmm(XmmRegister result,
                                              Register reg,
                                              Register temp,
                                              Label* not_double_or_smi) {
   Label is_smi, done;
   __ testq(reg, Immediate(kSmiTagMask));
   __ j(ZERO, &is_smi);
   __ CompareClassId(reg, kDoubleCid);
   __ j(NOT_EQUAL, not_double_or_smi);
   __ movsd(result, FieldAddress(reg, Double::value_offset()));
@@ skipping 203 matching lines @@
 void ParallelMoveResolver::Exchange(const Address& mem1, const Address& mem2) {
   __ Exchange(mem1, mem2);
 }
 
 
 #undef __
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64